I personally don't believe there's a one size fits all here, for those who are fast twitch fiber dominant, low reps / heavy weights work well, for those who are more slow twitch fiber dominant, high reps with moderate weights work well, and then there's everything in between.

Here's an interview that might be of interest, Dr Wayne Westcott has been conducting studies for decades in strength training, here he talks here about his findings as to what is the optimal number of reps to perform.

I think you need to vary it constantly for best results. Train your body to lift heavier and then you can focus on adding reps to that heavier weight, rinse and repeat. Changing things up is the best insurance against plateaus anyway, so that is a good enough reaon by itself. I also adore drop sets for a similar reason. In my limited experience of 6-7 years, drop sets have given me the most fulfilling workouts ever. I used to do 10x3, 8x4, 5x5, increasing the weight each time, then start over with more weight. It worked, just like nearly anytbing will as a youngster. I am a fast twitcher btw.